Former Test captain Brad Fittler suggests "one or two players" could force their way into Australia's World Cup squad with a big grand final performance - but nominates Sydney Roosters backrower Boyd Cordner a tour certainty whether he plays or not.

Cordner is desperate to prove his fitness ahead of Sunday's NRL decider against Manly, having been sidelined for seven weeks following ankle surgery.

His selection would take to six the number of genuine Kangaroos candidates on display - that list not including one man who would be an obvious selection in Manly skipper Jamie Lyon - who long ago declared himself unavailable for representative footy.

His reluctance to pull on the green and gold opens the door for the man he will mark on Sunday, Michael Jennings, who along with Josh Morris and Brent Tate will be eyeing the centre spot left open by the season-ending Achilles injury to Brisbane centre Justin Hodges.

Cordner's elevation to the 24-man touring squad would cap a breakthrough 2013 season - which has already seen him collect a first NSW Origin jumper and Dally M second-rower of the year award - beating out high-profile teammate Sonny Bill Williams to the honour.

Fittler claimed Cordner should be there regardless of what happens on Sunday.

"Regardless of whether he plays or not, one thing he shows is every game he's the same," Fittler said of Cordner.

"He doesn't have a bad game. He doesn't know how to have a bad game.

"The coach (Tim Sheens) will know that.

"He'll be there for sure I'd say."

Two of the men battling Cordner for a start will be on the opposite side, with Anthony Watmough and Glenn Stewart lining up for the Sea Eagles in what shapes as a mouth-watering match-up with Cordner and Williams.

Watmough would be considered a certainty to be on the plane to the UK and Ireland provided his injured knee allows, while Stewart, along with brother Brett, would both need stand-out performances to push their case.

Brett Stewart's chances of selection may be out of his control.

Billy Slater will be the first choice-fullback, while the selections of regular club fullbacks Darius Boyd and Greg Inglis in the squad as a winger and centre respectively could mean Sheens does not take a specialist back-up fullback.

"Week to week he's (Stewart) basically the best fullback, but then there's virtually two or three in front of him," Fittler said.

"It's quite an amazing scenario.

Asked about the impact of a strong display on Sunday, Fittler said:

"One or two players always have a big result in the grand final, it just shows you can play in a big game.

"A real big game in a grand final for one or two of them makes a big difference."

Manly's Daly Cherry-Evans seems assured to be the back-up to first-choice halves Johnathan Thurston and Cooper Cronk, with Mitchell Pearce's fine late season-form not enough to give him the nod.